Beds of discrete, randomly-arranged catalytic elements are frequently employed to promote chemical reactions. Such discrete catalytic elements have been used in a wide variety of geometric shapes, including spheres, rings, saddles, coils, cork screws, triangles, curlicues, rods, pellets, powders, extrudates and the like. The elements may themselves be catalytic or they may serve as a support, substrate or carrier for a catalytic material.
As examples of metal supports for catalytic material reference may be had to U.S. Pat. Nos. 3,994,831 and 2,974,150. U.S. Pat. No. 3,994,831 discloses a catalyst support formed in the shape of a perforated metal Leesing ring, i.e. a closed perforated cylinder which is bisected by a perforated surface. In one example according to the patent, a packed bed of such rings, made of a chromium-aluminum-iron alloy and coated with a mixture of platinum and palladium as a catalytically active material, is contacted by an ethylene-containing waste gas stream to convert the ethylene to carbon dioxide and water. U.S. Pat. No. 2,974,150 discloses a catalyst support in the form of a silver or stainless steel element having bonded thereto a silver-alkaline earth metal alloy as a catalytically active material. The coated elements in the form of a bed are useful in converting ethylene to ethylene oxide when the bed is contacted by a gaseous reaction mixture containing ethylene and oxygen. The elements are illustrated as having the shape of plain rings, spirals, cork screws, triangles, curlicues or Lessing rings.